2005/11/22 by Eilat Glikman, David J. Helfand, D. J. Helfand +2 · 8 citations
Mathematics · Physics and Astronomy · #Astronomy #Astronomy and Astrophysical Research #Astrophysics #Black-body radiation #Galaxies: Formation, Evolution, Phenomena #Galaxy #Geometry #Infrared #Line (geometry) #Mathematics #Optics #Physics #Quasar #Redshift #Spectral line #Spectral slope #Stellar, planetary, and galactic studies #Telescope #Wavelength #astro-ph
paper · pdf · doi:10.1086/500098
published as Astrophys.J.640:579-591,2006 · 39 pages, 11 figures, accepted for publication in ApJ Spectra will be made available in the online version of the journal, once published. Until then, if you wish to obtain the composite spectrum send an email request to eilatg[at]astro.columbia.edu
arxiv created 2005/11/22 · openalex publication_date 2006/03/27 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
We present a near-infrared quasar composite spectrum spanning the wavelength range 0.58-3.5 μm. The spectrum has been constructed from observations of 27 quasars obtained at the NASA IRTF telescope and satisfying the criteria K s < 14.5 and M i < -23; the redshift range is 0.118 < z < 0.418. The signal-to-noise ratio is moderate, reaching a maximum of 150 between 1.6 and 1.9 μm. While a power-law fit to the continuum of the composite spectrum requires two breaks, a single power-law slope of α = -0.92 plus a 1260 K blackbody provides an excellent description of the spectrum from Hα to 3.5 μm, strongly suggesting the presence of significant quantities of hot dust in this blue-selected quasar sample. We measure intensities and line widths for 10 lines, finding that the Paschen line ratios rule out case B recombination. We compute K -corrections for the J , H , K , and Spitzer 3.6 μm bands, which will be useful in analyzing observations of quasars up to z = 10.